Improving Elemental Ratio Measurements on Uranyl Fluoride with NanoSIMS

Abstract. Individual particles that on a mass basis consist dominantly of the components ammonium sulfate, organic material, and water are a common class of submicron particles found in today's atmosphere. Here we use (1) the organic-to-sulfate (org:sulf) mass ratio of the overall particle and (2) the oxygen-to-carbon (O:C) elemental ratio of the organic component as input variables in parameterisations that predict the critical relative humidity of several different types of particle phase transitions. These transitions include liquid-liquid phase separation (SRH), efflorescence (ERH), and deliquescence (DRH). Experiments were conducted by optical microscopy for 11 different oxygenated organic-ammonium sulfate systems covering the range 0.1 < org:sulf <12.8 and 0.29 < O:C < 1.33. These new data, in conjunction with other data already available in the literature, were used to develop the parameterisations SRH(org:sulf, O:C), ERH(org:sulf, O:C), and DRH(org:sulf, O:C). The parameterisations correctly predicted SRH within 15 % RH for 86 % of the measurements, ERH within 5 % for 86 % of the measurements, and DRH within 5 % for 95 % of the measurements. The applicability of the derived parameterisations beyond the training data set was tested against observations for organic-sulfate particles produced in an environmental chamber. The organic component consisted of secondary organic material produced by the oxidation of isoprene, α-pinene, and β-caryophyllene. The predictions of the parameterisations were also tested against data from the Southern Great Plains, Oklahoma, USA. The observed ERH and DRH values for both the chamber and field data agreed within 5 % RH with the value predicted by the parameterisations using the measured org:sulf and O:C ratios as the input variables.

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Exploring the controls on element ratios in middle Eocene samples of the benthic foraminifera <i>Oridorsalis umbonatus</i>

Climate of the Past ◽

10.5194/cp-8-1957-2012 ◽

2012 ◽

Vol 8 (6) ◽

pp. 1957-1971 ◽

Cited By ~ 2

Author(s):

C. F. Dawber ◽

A. K. Tripati

Keyword(s):

Benthic Foraminifera ◽

Bottom Water ◽

Middle Eocene ◽

Environmental Parameters ◽

Intermediate Water ◽

Saturation State ◽

Bottom Water Temperature ◽

Elemental Ratios ◽

Elemental Ratio ◽

Element Ratios

Abstract. Culturing studies and empirically based core top calibrations have been used to infer that elemental ratios in benthic foraminifera can be used as proxies to reconstruct past variations in bottom water temperature and saturation state (Δ [CO32−]). However the mechanisms linking elemental ratios to these parameters are poorly constrained. Here, we explore the environmental parameters influencing the incorporation of B, Li, Sr and Mg in Oridorsalis umbonatus in early Cenozoic sediments from Ocean Drilling Program Site 1209. We investigate the influence of middle Eocene variations in intermediate water Δ [CO32−] using relationships developed from core top samples. The fidelity of bottom water Δ[CO32−] reconstructions based on single element ratios is assessed by comparing the X/Ca-based reconstructions to each other and to carbon cycle proxy records (benthic foraminifera δ13C, organic carbon content, foraminifera dissolution indices), and a seawater δ18O reconstruction for Site 1209. Discrepancies in the reconstructed Δ[CO32−] values based on these different metal ratios suggest that there are still gaps in our understanding of the parameters influencing X/Ca and demonstrate that caution is required when interpreting palaeo-reconstructions that are derived from a single elemental ratio. The downcore record of O. umbonatus Mg/Ca does not exhibit any similarities with the Li/Ca, B/Ca and Sr/Ca records, suggesting that the environmental parameters influencing Mg/Ca may be different for this species, consistent with temperature as the strongest control on this elemental ratio. This hypothesis is supported by the coefficients of multiple linear regression models on published Mg/Ca data. An incomplete understanding of the controls on elemental incorporation into benthic foraminifera hinders our ability to confidently quantify changes in saturation state using single X/Ca reconstructions over a range of timescales.

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Physiological Changes and Elemental Ratio of Scrippsiella trochoidea and Heterosigma akashiwo in Different Growth Phase

Water ◽

10.3390/w13020132 ◽

2021 ◽

Vol 13 (2) ◽

pp. 132

Author(s):

Xiaofang Liu ◽

Yang Liu ◽

Md Abu Noman ◽

Satheeswaran Thangaraj ◽

Jun Sun

Keyword(s):

Organic Nitrogen ◽

Growth Period ◽

Heterosigma Akashiwo ◽

Physiological Changes ◽

Scrippsiella Trochoidea ◽

Average Cell ◽

Physiological Models ◽

Elemental Ratios ◽

Chl A ◽

Elemental Ratio

The elemental ratios in phytoplankton are important for predicting biogeochemical cycles in the ocean. However, understanding how these elements vary among different phytoplankton taxa with physiological changes remains limited. In this paper, we determine the combined physiological–elemental ratio changes of two phytoplankton species, Scrippsiella trochoidea (Dinophyceae) and Heterosigma akashiwo (Raphidophyceae). Our results show that the cell growth period of S. trochoidea (26 days) was significantly shorter than that of H. akashiwo (32 days), with an average cell abundance of 1.21 × 104 cells·mL−1 in S. trochoidea and 1.53 × 105 cells·mL−1 in H. akashiwo. The average biovolume of S. trochoidea (9.71 × 103 μm3) was higher than that of H. akashiwo (0.64 × 103 μm3). The physiological states of the microalgae were assessed based on elemental ratios. The average ratios of particulate organic nitrogen (PON) to chlorophyll-a (Chl-a) and particulate organic carbon (POC) to Chl-a in S. trochoidea (57.32 and 168.16) were higher than those of H. akashiwo (9.46 and 68.86); however, the ratio of POC/PON of the two microalgae was nearly equal (6.33 and 6.17), indicating that POC/Chl-a may be lower when the cell is actively growing. The physiological variation, based on the POC/Chl-a ratio, in different phytoplankton taxa can be used to develop physiological models for phytoplankton, with implications for the marine biogeochemical cycle.

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